1. Field of the Invention
Aspects of the present invention relate to a plasma display panel, and more particularly, to a plasma display panel capable of improving display quality by reducing or preventing halation of visible light, halation being a spreading of visible light emitted from discharge cells into adjacent discharge cells due to refraction and reflection of the visible light that propagates through a front substrate thereof.
2. Description of the Related Art
In general, a plasma display panel (hereinafter, referred to as a PDP) uses a vacuum ultra violet (VUV) ray emitted from plasma, the ray being generated by way of a gas discharge and a phosphor material excitation. The excited phosphor material generates red (R), green (G), and/or blue (B) visible beams, so that an image can be displayed.
With the PDP, a very large screen of greater than 60 inches can be formed to have a thickness of less than 10 cm. Since the PDP is a self emission device like a CRT (a cathode-ray tube), a color reproduction thereof is excellent, and distortions caused when viewing angles are changed do not occur. Further, the manufacturing process of the PDP is simpler than an LCD (a liquid crystal display), providing advantages in terms of productivity and cost. Therefore, the PDP is highly anticipated as being a next generation commercial flat display and a home television set.
In general, in an AC (alternating-current) surface discharge PDP, pairs of electrodes are disposed on a first substrate that face each other, and address electrodes are disposed on a second substrate that faces the first substrate. A space is interposed between the first and the second substrates. In the space between the first substrate and the second substrate, a plurality of discharge cells is arrayed at the intersections of the electrodes and the address electrodes. Each of the discharge cells is partitioned by barrier ribs. Inner sides of the discharge cells are coated with phosphor layers, and inner spaces of the discharge cells are filled with a discharge gas.
In the PDP, millions of the discharge cells are arrayed in a matrix pattern. The discharge cells are selectively turned on and off by using a memory effect of wall charges. During operation, the selected discharge cells are discharged, and visible light is generated.
Visible light generated from the discharge cells is transmitted through the first substrate, an upper dielectric layer covering the first substrate, and a protective layer, so that an image can be displayed.
When the visible light propagates through the first substrate, the upper dielectric layer, the protective layer, as well as air, and other layers, the visible light undergoes refraction, reflection, and/or scattering at interfaces between the layers. As a result, there is deterioration in transmittance of the visible light.
In addition, when the visible light propagates from a dense medium, such as the first substrate, into such a sparse medium, such as the air, a refraction angle of the visible light becomes larger than an incidence angle of the visible light. Moreover, visible light having the incidence angle that is larger than a critical incidence angle undergoes total reflection at the interfaces under such conditions.
In a related-art PDP, when the refraction angle of the visible light becomes large or when the visible light undergoes total reflection, the halation of the visible light occurs, halation being a spreading of the visible light into adjacent discharge cells. As a result, deterioration in display quality occurs.